Method for determining quantum bit operating point in quantum chip and quantum computer

Abstract

The application discloses a quantum chip quantum bit working point determination method and a quantum computer. First, a physical topology structure of a quantum chip is acquired, and the physical topology structure is used to reflect a physical layout of quantum bits in the quantum chip. Then, distances between each quantum bit in the quantum chip and a center position of the physical topology structure are acquired. Finally, working points of each quantum bit are acquired in sequence based on the distance size order, and the working point of the quantum bit is a working frequency of the quantum bit. The quantum bit working point determination method considers the whole chip, can meet the demand of a large-scale quantum chip, and makes up for the blank of the prior art.

Description

Technical Field

[0001] This invention relates to the field of quantum computing technology, and in particular to a method for determining the operating point of a qubit in a quantum chip and a quantum computer. Background Technology

[0002] Quantum computing and quantum information is an interdisciplinary field that uses the principles of quantum mechanics to perform computational and information processing tasks. It is closely related to quantum physics, computer science, and informatics. It has experienced rapid development in the last two decades. Quantum algorithms based on quantum computers, such as factorization and unstructured search, have demonstrated performance far exceeding that of existing algorithms based on classical computers, leading to expectations that this field will surpass current computing capabilities. Because quantum computing has the potential to far exceed the performance of classical computers in solving specific problems, realizing a quantum computer requires a quantum chip containing a sufficient number and quality of qubits, capable of performing high-fidelity quantum logic gate operations and readouts on these qubits. The quantum chip is to a quantum computer what a CPU is to a traditional computer; it is the core component of a quantum computer, the processor that performs quantum computations. Before each quantum chip is officially put into use, the parameters of the qubits within the chip must be tested and characterized.

[0003] For each qubit in a quantum chip, to complete as many calculations as possible within its finite lifetime, the fastest possible qubit logic gates are required. Generally, the execution time of a qubit logic gate is three to four orders of magnitude faster than the qubit's lifetime. However, fast qubit logic gate operations can lead to errors during execution. There are many reasons for qubit logic gate errors, such as parasitic coupling between nearest and second nearest neighbor qubits, spectral spread level system (TLS) defects, parasitic microwave modes, coupling with control lines and readout resonators, noise from frequency control electronics, frequency control pulse distortion, microwave control pulse distortion, and microwave carrier leakage. Most of these factors can be addressed by adjusting the qubit's operating frequency, i.e., its operating point. When each qubit in the quantum chip is at a suitable operating point, these effects can be effectively reduced. Currently, in order to improve the accuracy of quantum chips in performing quantum computing tasks, the operating point of a few qubits is generally considered. There is a lack of solutions that consider the quantum chip as a whole. Existing solutions are feasible when the number of qubits in the quantum chip is small, such as only a few or a dozen qubits. However, in the foreseeable future, the number of quantum chips will inevitably increase significantly. At that time, existing solutions will not be able to meet the needs of large-scale quantum chips.

[0004] Therefore, a scheme for determining the operating point of qubits that can be considered from the perspective of the entire quantum chip needs to be proposed.

[0005] It should be noted that the information disclosed in the background section of this application is intended only to enhance the understanding of the general background of this application, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the operating point of qubits in a quantum chip and a quantum computer, in order to solve the problem that existing solutions cannot meet the needs of large-scale quantum chips.

[0007] To address the above technical problems, this invention proposes a method for determining the operating point of a qubit in a quantum chip, comprising:

[0008] Obtain the physical topology of a quantum chip, wherein the physical topology reflects the physical layout of the qubits in the quantum chip;

[0009] Obtain the distance between each qubit in the quantum chip and the center of the physical topology;

[0010] Based on the order of the distances, the operating point of each qubit is obtained sequentially, and the operating point of the qubit is the operating frequency of the qubit.

[0011] Optionally, obtaining the operating point of each qubit sequentially based on the distance order includes:

[0012] The operating point of each qubit is obtained sequentially in ascending order of distance from the center of the physical topology.

[0013] Optionally, obtaining the operating point of each qubit sequentially according to the order of increasing distance between each qubit and the center of the physical topology includes:

[0014] First, obtain the operating point of the qubit that is close to the center of the physical topology, and then obtain the operating point of the qubit that is far from the center of the physical topology.

[0015] Optionally, the operating points of all qubits that are close to the center of the physical topology are used as parameters to obtain the operating points of qubits that are far from the center of the physical topology.

[0016] Optionally, when there are several qubits that are equidistant from the center of the physical topology, the corresponding operating point is obtained from the several qubits in a random order.

[0017] Optionally, the determining method further includes:

[0018] The physical topology of the quantum chip is divided into several sub-topology diagrams.

[0019] Optionally, obtaining the distance between each qubit in the quantum chip and the center of the physical topology includes:

[0020] Obtain the distance of each qubit in the sub-topology graph from the center of the sub-topology graph.

[0021] Optionally, when the operating point of each qubit in each sub-topology graph has been obtained, all the sub-topology graphs are spliced ​​together to complete the acquisition of the operating points of the qubits in the entire quantum chip.

[0022] Based on the same inventive concept, this invention also proposes a device for determining the operating point of a qubit in a quantum chip, comprising:

[0023] A topology acquisition unit is configured to acquire the physical topology of a quantum chip, the physical topology being used to reflect the physical layout of the qubits in the quantum chip;

[0024] A distance acquisition unit is configured to acquire the distance between each qubit in the quantum chip and the center of the physical topology.

[0025] The operating point acquisition unit is configured to acquire the operating point of each qubit sequentially based on the order of the distance, wherein the operating point of the qubit is the operating frequency of the qubit.

[0026] Based on the same inventive concept, the present invention also proposes a quantum control system, utilizing the method for determining the operating point of a qubit in a quantum chip as described in any of the above-described features, or the apparatus for determining the operating point of a qubit in a quantum chip as described in the above-described features.

[0027] Based on the same inventive concept, the present invention also proposes a quantum computer, including the quantum control system described in the above feature description.

[0028] Based on the same inventive concept, the present invention also proposes a readable storage medium storing a computer program thereon, which, when executed by a processor, can implement the method for determining the operating point of a qubit in a quantum chip as described in any of the above-described features.

[0029] Compared with the prior art, this application has the following beneficial effects:

[0030] This application proposes a method for determining the operating point of a qubit in a quantum chip. First, the physical topology of the quantum chip is obtained, reflecting the physical layout of the qubits. Then, the distance between each qubit and the center of the physical topology is obtained. Finally, based on the order of these distances, the operating point of each qubit is sequentially determined; the operating point is the operating frequency of the qubit. This method for determining the qubit operating point considers the entire chip and can meet the needs of large-scale quantum chips, filling a gap in existing technology.

[0031] The apparatus, quantum control system, quantum computer, and readable storage medium for determining the operating point of qubits in a quantum chip proposed in this application belong to the same inventive concept as the method for determining the operating point of qubits in the quantum chip, and therefore have the same beneficial effects, which will not be elaborated here. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the method for determining the operating point of a qubit in a quantum chip according to an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of the structure of a quantum chip shown in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of a device for determining the operating point of a quantum bit in a quantum chip according to another embodiment of the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0036] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] Please refer to Figure 1 This application proposes a method for determining the operating point of a qubit in a quantum chip, including:

[0039] S100: Obtain the physical topology of the quantum chip, which reflects the physical layout of the qubits in the quantum chip;

[0040] S200: Obtain the distance between each quantum bit in the quantum chip and the center of the physical topology;

[0041] S300: Based on the order of the distances, the operating point of each qubit is obtained sequentially, where the operating point of the qubit is the operating frequency of the qubit.

[0042] Unlike existing technologies, this embodiment proposes a method for determining the operating point of a qubit in a quantum chip. First, the physical topology of the quantum chip is obtained, reflecting the physical layout of the qubits. Then, the distance between each qubit and the center of the physical topology is obtained. Finally, based on the order of these distances, the operating point of each qubit is sequentially determined; the operating point is the operating frequency of the qubit. This method for determining the qubit operating point considers the entire chip and can meet the needs of large-scale quantum chips, filling a gap in existing technologies.

[0043] by Figure 2 Taking the quantum chip shown in the image as an example, Figure 2 The diagram shows the physical topology of a quantum chip containing 36 qubits in one embodiment. Point A is the center of the physical topology. According to the scheme of this application, we sequentially obtain the distance of each qubit in the quantum chip from point A, and then sequentially obtain the operating point of each qubit based on the distance. The operating points can be obtained in descending order of distance, or in ascending order of distance. It should be noted that when there are several qubits at the same distance from the center of the physical topology, the corresponding operating points are obtained from these qubits in a random order. For example, Figure 2 The quantum bit Q in 33 Q34 Q 43 Q 44 Since these four qubits are equidistant from point A, they can acquire their corresponding operating points in a random order without restriction.

[0044] Furthermore, in the method for determining the operating point of a qubit in this application, the operating points of qubits closer to the center of the physical topology are obtained first, followed by the operating points of qubits farther from the center of the physical topology. This maximizes the performance of the quantum chip and ensures that qubits whose suitable operating points cannot be determined appear at the edge of the physical topology of the quantum chip, effectively improving the utilization rate of resources in the quantum chip. Specifically, in this embodiment, obtaining the operating point of each qubit sequentially based on the distance order includes:

[0045] The operating point of each qubit is obtained sequentially in ascending order of distance from the center of the physical topology.

[0046] Specifically, in this embodiment, obtaining the operating point of each qubit sequentially according to the order of increasing distance between each qubit and the center of the physical topology includes:

[0047] First, obtain the operating point of the qubit that is close to the center of the physical topology, and then obtain the operating point of the qubit that is far from the center of the physical topology.

[0048] Specifically, in this embodiment, the operating points of all qubits that are close to the center of the physical topology are used as parameters to obtain the operating points of qubits that are far from the center of the physical topology.

[0049] When allocating the operating points of qubits, we primarily consider residual ZZ coupling and XY crosstalk, which are the two main causes of gate execution errors. Residual ZZ coupling refers to unwanted coupling that still exists after the coupling between qubits has been turned off. Coupling between two qubits is a necessary condition for implementing a two-qubit gate, but when the two-qubit gate is not working, the coupling between them needs to be turned off to avoid exciting unnecessary terms, thereby ensuring computational accuracy. XY crosstalk refers to the phenomenon where the driving frequency applied to one qubit causes other neighboring qubits to produce anharmonic driving.

[0050] To control the effects of XY crosstalk, when the target qubit i is excited, its driving frequency should be prevented from causing its nearest neighbor qubit j to transition from state 0 to state 1 and from state 1 to state 2. We set the following constraints:

[0051] fi -f j |≥δ A1 (1)

[0052] f i -f j -α j |≥δ A2 (2)

[0053] Where, δ A1 δ A2 To set two thresholds, f i f is the frequency of the target qubit i. j Let α be the frequency of qubit j. j For the nonharmonicity of qubit j, in this embodiment, δ A1 δ A2 It can be set to 40MHz. In other embodiments, other values ​​can be set according to the actual situation, and there are no restrictions here.

[0054] To control the effects of residual ZZ coupling, the residual ZZ coupling between the target qubit i and its diagonal qubit k is considered. Figure 2 For example, assuming the target qubit i is qubit Q33, then the diagonal qubit k is Q 22 Q 24 Q 42 Q 44 We need to control the residual ZZ coupling value to be less than a set value to control its effect, and set the following constraints:

[0055]

[0056] Among them, g ik f is the value of the residual ZZ coupling between the target qubit i and its diagonal qubit k. k For the frequency of a quantum bit k, δ Z1 In this embodiment, δ is the set threshold. Z1 It can be set to 0.01MHz. In other embodiments, other values ​​can be set according to the actual situation, and there are no restrictions here.

[0057] Based on the constraints of Formulas 1, 2, and 3 above, the objective equation is constructed as follows:

[0058] Func = -f i ;

[0059] What we need is that, under the above constraints, the closer the frequency of the target qubit is to its degeneracy point, the less noise interference the qubit will experience in the entire quantum chip.

[0060] Those skilled in the art will understand that the operating points of all qubits that are closest to the center of the physical topology are obtained first, as they are subject to fewer constraints and are easier to obtain.

[0061] Furthermore, to better meet the demands of large-scale quantum chips, this application proposes dividing the physical topology of the quantum chip into several sub-topological diagrams, which can further reduce the difficulty of determining the operating point of the qubit. Specifically, in this embodiment, the determination method further includes:

[0062] The physical topology of the quantum chip is divided into several sub-topology diagrams.

[0063] Specifically, in this embodiment, obtaining the distance between each qubit in the quantum chip and the center of the physical topology includes:

[0064] Obtain the distance of each qubit in the sub-topology graph from the center of the sub-topology graph.

[0065] Specifically, in this embodiment, when the operating point of each qubit in each sub-topology graph has been acquired, all the sub-topology graphs are spliced ​​together to complete the acquisition of the operating points of the qubits in the entire quantum chip.

[0066] By utilizing the physical topology segmentation and stitching method of this application—dividing the graph elements into different sub-topological graphs and solving each sub-topological graph separately using different servers—the solution can be accelerated. For example, with... Figure 2 For example, the graph elements can be divided into 3 groups along the diagonal. After solving the two groups on the sides separately, they can be combined to solve the remaining part, and finally complete the entire solution process.

[0067] Based on the same inventive concept, please refer to Figure 3 This application also proposes a device for determining the operating point of a qubit in a quantum chip, comprising:

[0068] The topology acquisition unit 100 is configured to acquire the physical topology of a quantum chip, the physical topology being used to reflect the physical layout of the qubits in the quantum chip.

[0069] Distance acquisition unit 200 is configured to acquire the distance between each qubit in the quantum chip and the center position of the physical topology;

[0070] The operating point acquisition unit 300 is configured to acquire the operating point of each qubit sequentially based on the order of the distance, wherein the operating point of the qubit is the operating frequency of the qubit.

[0071] It is understood that the topology acquisition unit 100, the distance acquisition unit 200, and the operating point acquisition unit 300 can be implemented in a single device, or any one of these modules can be split into multiple sub-modules. Alternatively, at least some of the functions of one or more modules of the topology acquisition unit 100, the distance acquisition unit 200, and the operating point acquisition unit 300 can be combined with at least some of the functions of other modules and implemented in a single functional module. According to embodiments of the present invention, at least one of the topology acquisition unit 100, the distance acquisition unit 200, and the operating point acquisition unit 300 can be at least partially implemented as hardware circuitry, such as a field-programmable gate array (FPGA), a programmable logic array (PLA), a system-on-a-chip, a system-on-a-substrate, a system-on-package, an application-specific integrated circuit (ASIC), or can be implemented in hardware or firmware in any other reasonable manner by integrating or packaging the circuitry, or in a suitable combination of software, hardware, and firmware implementations. Alternatively, at least one of the topology acquisition unit 100, the distance acquisition unit 200, and the working point acquisition unit 300 can be at least partially implemented as a computer program module, which can perform the functions of the corresponding module when the program is run by a computer.

[0072] Based on the same inventive concept, embodiments of this application also propose a quantum control system, utilizing the method for determining the operating point of a qubit in a quantum chip as described in any of the above-described features, or including the apparatus for determining the operating point of a qubit in a quantum chip as described in the above-described features.

[0073] Based on the same inventive concept, embodiments of this application also propose a quantum computer, including the quantum control system described in the above feature description.

[0074] Based on the same inventive concept, this application also proposes a readable storage medium storing a computer program thereon, which, when executed by a processor, can implement the method for determining the operating point of a qubit in a quantum chip as described in any of the above-described features.

[0075] The readable storage medium can be a tangible device capable of holding and storing instructions for use by an instruction execution device, such as, but not limited to, electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination thereof. The computer programs described herein can be downloaded from the readable storage medium to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. Each computing / processing device's network adapter card or network interface receives the computer program from the network and forwards it for storage in a readable storage medium within the respective computing / processing device. The computer program used to perform the operations of this invention can be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as "C" or similar languages. The computer program can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuits, such as programmable logic circuits, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), are personalized by utilizing state information from a computer program. These electronic circuits can execute computer-readable program instructions, thereby realizing various aspects of the present invention.

[0076] Various aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, systems, and computer program products according to embodiments of the invention. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by a computer program. These computer programs can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that, when executed by the processor of the computer or other programmable data processing apparatus, they create means for implementing the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. These computer programs can also be stored in a readable storage medium that causes a computer, programmable data processing apparatus, and / or other device to operate in a particular manner; thus, the readable storage medium storing the computer program comprises an article of manufacture including instructions for implementing aspects of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams.

[0077] A computer program may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the computer program executing on the computer, other programmable data processing apparatus, or other device to perform the functions / actions specified in one or more boxes of a flowchart and / or block diagram.

[0078] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," or "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0079] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for determining the operating point of a qubit in a quantum chip, characterized in that, The method comprises: obtaining a physical topology of a quantum chip, the physical topology being used to reflect a physical layout of quantum bits in the quantum chip; obtaining a distance of each quantum bit in the quantum chip from a center position of the physical topology; obtaining, in sequence, a working point of each quantum bit based on a size order of the distance, the working point of the quantum bit being a working frequency of the quantum bit.

2. The determination method of claim 1, wherein, The step of obtaining, in sequence, the working point of each quantum bit based on the size order of the distance comprises: obtaining, in sequence, the working point of each quantum bit according to a size order of the distance of each quantum bit from the center position of the physical topology.

3. The determination method of claim 2, wherein, The step of obtaining, in sequence, the working point of each quantum bit according to the size order of the distance of each quantum bit from the center position of the physical topology comprises: obtaining the working point of a quantum bit close to the center position of the physical topology first, and obtaining the working point of a quantum bit far from the center position of the physical topology later.

4. The determination method of claim 3, wherein, The working point of all quantum bits close to the center position of the physical topology is used as a parameter for obtaining the working point of a quantum bit far from the center position of the physical topology.

5. The determination method of claim 2, wherein, When there are several quantum bits with the same distance from the center position of the physical topology, corresponding working points are obtained from the several quantum bits in a random order.

6. The determination method of claim 1, wherein, The method further comprises: dividing the physical topology of the quantum chip into several sub-topology graphs.

7. The determination method of claim 6, wherein, The step of obtaining the distance of each quantum bit in the quantum chip from the center position of the physical topology comprises: obtaining a distance of a quantum bit in each sub-topology graph from a center position of the sub-topology graph.

8. The determination method of claim 7, wherein, When the working point of each quantum bit in each sub-topology graph has been obtained, all the sub-topology graphs are spliced to complete the obtaining of the working point of the quantum bit in the entire quantum chip.

9. A device for determining the operating point of a qubit in a quantum chip, characterized in that, The device comprises: a topology obtaining unit configured to obtain a physical topology of a quantum chip, the physical topology being used to reflect a physical layout of quantum bits in the quantum chip; a distance obtaining unit configured to obtain a distance of each quantum bit in the quantum chip from a center position of the physical topology; a working point obtaining unit configured to obtain, in sequence, a working point of each quantum bit based on a size order of the distance, the working point of the quantum bit being a working frequency of the quantum bit.

10. A quantum control system, characterized by, The device utilizes the method for determining the working point of the quantum bit in the quantum chip according to any one of claims 1-8, or the device for determining the working point of the quantum bit in the quantum chip according to claim 9.

11. A quantum computer, characterized by The quantum control system comprises the quantum chip according to claim 10.

12. A readable storage medium, having stored thereon a computer program, characterized in that, The computer program is executed by a processor to implement the method for determining the working point of the quantum bit in the quantum chip according to any one of claims 1-8.

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